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The Aspergillus flavus toxins are responsible for an annual loss of 25% of global crops through contamination. Toxigenic fungi are ubiquitous, In food supplies worldwide, mould infestation of susceptible agricultural products such as grains, cereals, nuts, and fruits is prevalent. There are thousands of mycotoxins, but only a few raise serious food safety problems. Mold growth can result in decreased crop yields and decreased productivity of livestock. Among the mycotoxins that affect not only food production but also food manufacturing are aflatoxins. Wheat grains are often harvested at moisture content which can be allow the growth of moulds and the mycotoxin production. If the grains are dried to healthy moisture content (14-16 percent), the fungal growth is delayed or inhibited ,and the toxin production will be inhibited too. In order to keep the grain safe and free from destruction and food poisoning, temperature and humidity during maize storage must therefore be controlled during storage. Therefore, the aim of the present study was to investigate the effectiveness of the treatment of organic acid as preservatives to control fungal pollution in imported wheat grains that can be used during storage as a fungicide for wheat grains.
The main objectives of the present study can be summarized as follows:
1-Evaluation of Russain wheat imported from physical and chemical properties points of view.
2-Determine the physico-chemical and rheological properties of different wheat flours to provide us with data that may employ as guidelines in bread processing.
3-Evaluate of bread produced from different flours by determine the physical, chemical and sensory properties as well as quality of the produced bread.
4-Effect of organic acid treatment on the fungal growth and aflatoxins production of imported wheat
5.1.1. Evaluation of Russain wheat (imported) for bread making:
22.214.171.124 Physical properties of wheat kernels:
No significant difference was observed in foreign material among all samples, which was 0.02% before storage and 1.0%after storage. Test weight was 61.75P/B before storage and 60.7P/B after storage, 1,000 kernel weight was 33.5g. The flour yield was differed slightly among the tested sample which was 65.9 to 70.0%. So data present that the three of ascorbic wheat treatment and control had highest flour yield (70.0%) while the propionic wheat treatment (0.04%) had lowest flour yield (65.9%).
Hardeness of different wheats was 61.0%, of Russain wheats which was (red colour.
126.96.36.199 Chemical composition of wheat kernels:
Russain wheat contained before storage:
The percent of protein (11.70%), ash (1.67%) and the total nitrogen free extract (71.97%). Falling number of Russain wheat samples was 351.0sec.
188.8.131.52 Physical and chemical properties of different wheat flours:
The increase in white colour and decrease of yellow colour were reduced as a result of milling and extraction of the flour. Data showed that the white wheat variety has the highest white colour value for flour colour than the wheat red variety, which is less white.
Russain wheat flour characterized by higher crude protein at propionic wheat treatment (0.03 & 0.04%) flour had the highest protein content (11.2%).
The falling number values were ranged from 300 to 361 sec. The ascorbic wheat treatment (1.0%) flour had the highest value (361sec.) where the ascorbic wheat treatment (3.0%) flour had the lowest value (300sec.).
Wet and dry gluten contents of different flours ranged from 23.6 – 25.2% and 7.6 – 8.5%, respectively. The ascorbic wheat treatment (2.0%) flour showed protein content of 10.7% and had the higher wet, dry gluten and hydration ratio (25.2, 8.5 and 1.96 % respectively) compare to other samples.
184.108.40.206 Rheological properties:
Rheological characteristics of doughs were clearly influenced by the variety of wheat. The samples which can be classified as good sample for bread making in considering to their rheological properties (long stability, low degree of weakening, maximum resistance to extension, high dough energy and maximum viscosity( is acetic wheat treatment flour has very good quality and very strong wheat flowed by propionic wheat treatment flour while the ascorbic wheat treatment flour has bad quality and poor quality.
5.1.2. Quality of imported wheat during storage for 90 days:
A stepwise preliminary experiment was doing a survey for twenty imported wheat grains ( Triticum aestivum ) different cultivers were obtained from Russian. They were taken from Company since 2017. Each sample was analyzed for grading, type of fungi, mycotoxin, Chimical compostation and the following were recorded for each sample: moisture, during storage. The changes of moisture, grading, mold count and mycotoxin in the twenty samples of each location during storage for 0, 30, 60, and 90 days were estimated. The results showed that Moisture content ranged from 8.6% after storage to 11.6% before stroge (in imported Russain wheat grains). The moisture content decreased in wheat by long period time of storage but no more than 3 months.
Data showed that all imported wheat were aflatoxins free and the mold count was between 3.48 before storage and 3.50 after storage log cfu/g. The total damage varied between 1.86% before storage and 8.0% after storage and the grading between grade 1 before storage and grade 3 after storage. The most isolated fungal strains were belonging to genus Aspergillus. Asp. flavus was the most common fungi found in most samples in all among of samples. While after storage Acremonium butyri was the most common fungi .this could be due to the milling sources of wheat miller.
Therefore this work was concentrated on the Aspergillius and its toxins for 90 days. wheat samples were sample grade because insect infestation and total damage was the highest compared with all other samples.
All samples were decreasing of falling number value by long time of the storage period for the among of different wheat kernels and increasing of enzyme activity.
There was no effect of storage on the protein content but there was decreasing of fat % in all among of different wheat kernels during storage for 90 days at 25˚c. it coud be due to nutrition of development of micro organism which found on the samples to development it’s colonies.
Data showed that the samples after storge were the lowest in quality (total damage % and insect infestation) in comparison with the other before storage, but the mold count have clear trend between the different samples.
There are a new isolated fungal Acremonium butyri. The results concluded that cylinders of milling are sources of increases fungal species pollution and total mould count because there are new isolated fungal species in some sample not found before and total mould count was increasing after milling than the total mould count had before.
Data showed that toxin production of aflatoxin determination (B1,B2,G1,G2 and total) after milling were increased that the results which determined after 90 days storage in all among of samples so cylinders of milling are sources of increasing aflatoxin determination
5.1. 3 Effect of some organic acid treatment on the fungal growth and aflatoxins production of imported wheat:
Analysis of the effect of some organic acid treatments on the fungal count and mycotoxin content of wheat before and after storage for different periods of time:
Twenty thousand grammes (20000 g) of samples of wheat and wheat flour were subdivided into 20 sub-samples and treated as follows:
1- One Kg of subsample wheat was stored as a negative control sample containing natural flora.
2- Nine Kg of artificially inoculated wheat subsample with 105 cfu/100 g toxigenic Aspergillus flavus given NRRL (20521) and stored as a control positive sample and stored for 90 days after which the mycotoxin content was estimated and treated with different doses of different orgainic acids.
3- One Kg flour wheat subsample stored as control negative
Sample contain natural flora.
4- Nine Kg of flour wheat subsamples were not artificially inoculated with NRRL (20521) of 105 cfu/100 g of toxigenic Aspergillus flavus and stored as a control positive sample and stored for 90 days after which mycotoxin content was estimated and treated with different doses of orgainic acid.
5-Moisture content of wheat samples were modified to be 16.5%. and stored at incubating temperature 25°C up to 90 days and the fungal growth and toxin production were determined.
6-Different concentrations of the acetic acid, propionic acid and Ascorbic acid were prepared using autoclaved distilled water as a diluent. The prepared concentrations were (0.02%, 0.03%, and 0.04%) for propionic acid, (0.04%, 0.05% and 0.06%) for acetic acid, (1%, 2% and 3%) for Ascorbic acid.
The results showed that: control and At the beginning of the storage era, all treated samples were under the detection limit (0.5ppb) for aflatoxin samples at 25 ° C. Also the highest mold count was 8.33 log cfu/g for the control samples. Generally the effect of organic acids treatments is not remarkable at the beginning of the storage period of the experiment in all samples.
The data presents the effect of some organic acids used as preservatives for imported wheat grains on mold growth and Aflatoxins production after 30 days of 25 ° C storage. It could be observed that the rise in propionic and acetic acid doses had remarkable effect on mold count .the increase of acid doses decreased the mold count. The highest decrease in mold count was recorded in samples treated with acetic acid followed by propionic acid. On the contrary the use of increased doses of Ascorbic acid had the least effect on mold growth. The use of 0.04% doses of Acetic acid had the highest effect in decreasing mold counts after 30 days of the storage.
The effect of some organic acid used as preservatives for imported wheat on mold growth after 60 days of the storage at 25°C. The use of acetic acid had the highest effect on mold growth when compared with all other treatments. Also the increase of organic acid doses decreased the mold growth after 60 days of storage at 25°C. Furthermore, Ascorbic acid had reverse effect on mold growth as compared with control wheat samples. Generally Aflatoxins production for B1, B2, G1, G2 and total Aflatoxins were not determined in all samples after 60 days of the storage at 25°C. Generally the use of organic acid 0.05% doses of propionic acid had the highest effect on mold growth and mold counts were less than 1.0 log cfu/g.
The data showed that after 90 days of storage at 25°C of imported wheat the mold count ranged from 8.18 to <1.0 log cfu/g.(in control and 0.04 and 0.05% acetic acid respectively.) also total aflatoxins determination ranged from 100 ppb to 0.5 ppb. (For control and 0.05% acetic acids samples respectively). The use of 0.04 and 0.05% acetic acids decreased the mold count to less than 1.0 log cfu/g and different aflatoxins determination was nil in the samples after 90days of storage at 25°C. but the use of organic acid decreased the mold count and Aflatoxins production when compared with control samples. Aflatoxins production was the lowest with the use of the 0.05% acetic acid followed by the used of 0.04% and 0.06% acetic acid. On the other hand the use of ascorbic acid decreased aflatoxins production as compared with control samples after 90 days of storage at 25°C.
Effect of some organic acids used as preservative for imported wheat flour on mold growth and aflatoxins production at the beginning of storage at 25°C. Generally the use of all organic acid even, 0.02% propionic acid and 1% ascorbic acid decreased the mold counts to less than 1.0 log cfu/g. Further more different aflatoxins production was not determined in all imported wheat at the beginning of storage at 25°C.
Mold count was 0.72 log cfu/g in control. Also the use of 1.0%, 2.0%, 3.0% of ascorbic acid had no effect on mold count after 30 days of storage at 25°C. On the contrary the use of 0.03% and 0.04% propionic acid and 0.05, 0.06% acetic acid decreased the mold count to less than 1.0 log cfu/g. Also the mold count decreased by increasing of propionic acid and acetic acid doses at treated samples. While Aflatoxins determination was not carried out in all samples.
The effect of some organic acids used as preservative for imported wheat on mold growth and aflatoxins production after 60 days of storage at 25°C. Mold count was the highest (2.06 log cfu/g) in (0.02) propionic acid samples and with the use of 1.0%, 2.0%, 3.0% of ascorbic acid. On the contrary, mold count was less than 1.0 log cfu/g in wheat samples treated with 0.04% propionic acid and 0.04, 0.05, 0.06% acetic acid . Aflatoxins determination (B1, B2, G1, G2 and total Aflatoxins) were not determined in all treated samples at the end of the storage period.
5.1.4 : Physical properties of bread making from treatments wheat flour
Bread is the main source of energy in the diet of many peoples, especially in developing countries. The bread industry faces serious technological problems including bread staling, lack of flavor compounds and the desired taste, which lead to increase the losses of bread. There are many research efforts to overcome these problems. The current study was initiated to establish the conditionings of dough technology in the production of wheat bread to improve flavor, texture, colour crust, weight after baking, volume, specific volume, loaf volume appearance, crumb, texture, crumb grain, crust colour, aroma, eating quality and total scores to evaluate sensory properties of bread production of toast bread are highest value by acetic (0.05%) toast bread.